Method for cleaning metals.



A. A. NELSON.

METHOD, FOR CLEANING METALS.

APPLICATION FILED 53.25, 1914.

1 1.1 4, 6 3 5 Patented Oct. 20, 1914.

uuewtoz flflMSd/O vvbbvwoozo M p Shrew M1 b electrolytic action with acid solutions as tli e These methods, however,

. UNITE STATES" PATENT oFrIonJ-j ABOEN'A. NELON, or cmcaeo, rLLInois, assrenon r0 Acne smear GQODS comra'nit or cmcaao, rumors, a coaroaarron' or rumors. v

fnn'rnon For; cnnanrne METALS.

Specification of Letters EPatent. Application filed February 25, 1914. Serial No. 820,988.

To all whom it may concern: v Be it known that I, Aron A. NELSON,'C1tI- zen of the United States, residing at Chi cage, in the county of Cook and State of Illinois, have invented certain new and useful Improvements-in Methods for Cleaning Metals, of which the following is a specification.

My invention. relates to a new and im proved method of and compound for removing scale, rust, oil or other impurities from 11'011 or steel, the object of my inven .cleanin ma e. continuousl carried out y 3 and long strips of metal, wire and the like therefore cleaned. Y

Previous to this time metals have been cleaned by pickling them in an acid bath or electrolyte. have been ojectionable because of the fact that the acid attacks the metal being cleaned and in the case of sulfuric acid, renders the metal more brittle. Moreover, the acid attacks the tank containing it. Because of this eating awe of the metal being treated and the tank, the acid solution in a short time becomes so impure as to be useless and must therefore be continually renewed.

A further object of my invention is, therefore, the provision of a method for cleaning iron and steel without the employment of acids of any nature.

A further object of my invention is the provision 01 a method which will be much more rapid and consequently more economical than any of the acid pickling methods now in use.

In carrying; out my invention, the metal being cleaned lytiebath serving as the cathode. In thisis passed through an electroconnection, a further object of my invention is the employment of an electrolyte of such nature that in a laterstep in the process it may be recovered as a b product and again em loyed as an electrolyte, there be:

but s ight waste for this reason.-

%n the pickling methods now commonly em loyed, the cleaning action takes place while the article being cleaned is in-the tion which forms the electrolyte.

I Oneob ect of m present invention is the Patente oat 2. .11-

electrolytic bath and such article .is then" washed n water to remove the -,acid solu-- provision of a met 0d in which the cleaning of the article takes place not in the electro-- lytic bath but during the subsequent Washing of the metal in water. Because of this,

the. electrolyte itself does not become contaminated by theimpurities which are removed from the metal. Y

With these and other objects in "iew, my

invention will-be more fully described, illustrated m the accompanying drawing, and

then specifically pointed. out in the claims which are attached to and forma part of this application.

operation, a continuous stri of sheet metal being illustrated as the artic eb'eing cleaned.

My invention consists primarily in' two steps, the metal toybe cleaned bein first The drawing illustrates, diagrammati-'. cally, one" simple form of apparatus for cal'rylng out my improved'metal cleaning passed through an electrolytic bath ormed by the fusion of some salt of one of the alkaline metals, the metal being cleaned forming the cathode during its passage through this bath and as a consequence reoeiving a thincovering or surface film of I the alkaline metal employed. Immediately after its assage from this electrolytic bath, the meta being cleaned is passed through a bathof hot water durin which the film of-alkaline metalcovering 1t combines with the water with such rapidity or violence asto remove rust, scale,- oil or other impurities from the surface of the metal. The metal is then ready, without further :treatment, for passage into a galvanizing bath or into asecondelectrolyticbath arranged to electroplateuit. V a a The alkaline metal employed as the electrolyte is referably either'sodium or potassium, the hydroxid salt being preferred. it will of course be understood, however, that I do not wish toElimit myself to any particular salt of any particular alkaline metal,

formed of iron and supported over a'heater although I usually employ sodium hydroxid.

l 11 of any suitable type. Themetal to'be cleaned is-passed through a bath of-fused sodium hydroxid 12 contained in this container or pair and incase a long strip of sheet' metal, screening or wire is being cleaned, the metal is held beneath the'sur-- face of the bath by a suitable frame 13 mounted for movement toward and away from the bottom ofthe pan and provided at its lower ends with spaced rollers 14 extending into the fused sodium hydroxidandbeneath which the metalbeing cleaned. here indicated as a strip of sheet metal 15,

' and then beneath rollers 21 which hold the;

' passes. Upon leaving this electrolaytic bath,

the strip of metal passes over ani ler roller 16 and then beneath spaced rollers 17 which hold it beneath the surface of the water contained in a second pan 18, this water being maintained at approximately its boiling point in any suitable manner as by a steam coil 19. From this second bath, the strip of.

metal passes. over a second idler roller 20 metal beneath the surface of a third bath contained in a an- 22, from which bath it passes over an i ler roller 23 and so to a reel in connection with the electrolytic bath of- 24. This third bath, in efiect, forms no i sure proper submersion of the metal in'the' various baths. These rollers may be mounted upon a-frame such as the frame 13 shown sodium hydroxid or they may be supported directly by the pans themselves as shown in' the other baths. The pan 10 is rovided with a bindin' post 25 and the me 13 supporting an in electrical connection with the rollers 14 with a. second bindin post 26. Conductor wires 27 "and 28 lead om any suitable source of electric current, such as a generator 29 to the binding ppst 25 and 26,- respectively. It will therefore be seen that the sheet metal, while passing through the sodium hydroxid bath, acts asfthe cathode,

the positive wire beingv connected. the

pan 10. b a

As a result of the electrolytic action, the

- sodium hydroxid is ionized, the sodium ions passing to the stri of metal being cleaned and forming a sur ace film or coating. over it. Upon passage of the sodium coated strip of iron or steel being cleaned into the water bath 18, this free metallic sodium combines with the water, the action being very rapid and therefore causing the throwing ofi of all im urities from the surface of the sheet metal, caving the metal in proper condition for metallic coating either by nassage througha bath of molten metal or by electroplat ng. 4

Although the primary advantage of this [process over those now in use, as previously pointed out, consists in the fact that no acids are employed, which acids are detrimental'to the metal being cleaned and to the pan or receptacle containing the bath, other advantages which accrue are worthy of notice. Chief among these is the fact that the sodium combining with the water in the pan 18; forms sodium hydroxid which may be readily separated from the impurities cast off from the metal being cleaned in any suitable manner as by filtering. This sodium hydroxid solution may then be concentrated and the sodium hydroxid crystallized from the-solution. The sodium hydroxid thus recovered may then be again employed in the pan 10, very little loss of the electrolyte being therefore necessary. Furthermore, inasmuch as the actual removal of the foreign matter from the metal being cleaned takes place in the washmg pan 18 and not the electrolytic bath, it will be clear that the fused sodium hylzrpxid remains cleanand efiicient as long as 1 asts.

I find that under ordinary conditions, the

metal being cleaned need be immersed in the electrolytic bath for not over thirty seconds to msure thorough removal of all impurities upon its passage into the water bath. It w ll there ore beclear that the operation is exceptionally rapid as with acid baths, with or without electrolytic action, the metal mustbe immersed for between a half hour or an hour after which it must be'further treated to 7 other metal c coating.

It will of course be understood that although I haye illustratedbut one form ofapparatus, I do not wish to be limited to the pirepar'e it for electroplating or.

form shown, my invention consisting rather in the employment of fused sodium nydroxld .as an electrolyte for cleaning the metal and the subsequent reaction of the 'dewith water. j Havi thus described the whatiscaimedasnewis:

1. method'of removin scale, rust' and the hke flOlll llfOll and stee which consists -m passing an electric current to the iron or steel connected as a cathode in analkaline I invention,

electrolyte, and in then submerging the iron or steel in a bath of water.

2; A method of-removing scale, rust and stee the like from iron and which consists fused alkaline metal salt and in then submergm'g the iron or steel in a bath of water.

in passing an electric current to the iron or steel connected as a cathode,,in a bath of a .fused' hydroxid salt of'an alkaline metal,

3. method of 'removin scale, rust and the hke from Iron and stee which consists in passing an electric current to the iron o steel connected as acathode in a bath of a electric current being passed through the bath with the iron or steel as the cathode,

and in subsequently passing the iron or steel through a cleansing bath,

method of removin scale, rust and the like from iron and stee which consists in passing the iron or steel through anelectrolytic bath of fused sodium hydroxid, an electric current being passed through the bath with the iron or steel as the cathode, and in subsequently passing the iron or steel throu h a bath of water.

7. g method of removin scale, rust and the like from iron and stee which consists in passingthe iron or steel through a bath of fused sodium hydroxid forming an electrolyte in an iron container, an electric current being passed through the electrolyte with the container as the anode and the iron or steel as the cathode, and in subsequently subjecting the iron or steel to the action of water.

. 8. Amethod of removing scale, rust and the like from iron or steel, which consists in coating the iron or steel with an alkaline metal, and in subjecting the iron or steel so coated to the action of water..

9. A method of removing scale, rust and the like from iron and steel, which consists in first coating the honor steel with an alkaline metal by electrolysis and in subsequently submitting the iron or steel so coated to the action of water.

10. A method of removing scale, rust and the like from iron and steel, which consists in forming an electrolytic deposit of sodium on the iron or steel and in subjecting the iron or steel to the action of water.

11. 'A method of removing scale, rust and the like from iron and steel, which consists in exposing the iron or steel to the action of water in the presence of an alkaline metal.

12. A method of removin scale, rust and the like from iron and stee which consistsin exposing the iron or steel-to the action of water in the presence of sodium.

13. A method of cleaning metals which consists in exposing the metal to the action of moisture in the presence of an alkaline metal.

14:. A method of cleaning metals which consists in forming an electrolytic deposit of an alkaline metal upon the metal to be cleaned and in then removing such deposit by the action of moisture,

In testimon whereof I aflix my signature in presence 0 two wltnesses.

ARON. A. NELSON. [L. 5.]

. Witnesses: I

' T. J. OR'roN,

CHAS. A. Rose. 

